An improved method of measuring dynamic elastic constants, using electrostatic drive and frequency-modulation detection

Abstract

Apparatus is described for the measurement of the natural longitudinal resonant frequencies of metal bar specimens. The specimen is driven by the application of an alternating electrostatic force between one end and a small fixed plate parallel to it. The resonance is detected by a frequency-modulation system, working at 60 Mc/s, using the same plate as for the drive. The specimen mounting and drive arrangements are described and details given of the frequency-modulation and detection circuits.